THE VOCAL APPARATUS 139 



labored breathing it widens during inspiration and narrows 

 during expiration. 



187. Vocalization. There may be a sort of speech with- 

 out the action of the larynx or the vocal cords, when the 

 muscles of respiration, the lips, and what are called the 

 resonating cavities above the larynx are alone brought into 

 play. This produces whispering. But for vocalization 

 the vocal cords must be brought very near together, made 

 tense and parallel, and a current of air must be forced 

 swiftly through the narrow slit, throwing them into rapid 

 vibration. This is effected by means of a complicated 

 arrangement of muscles and ligaments attached to the 

 various cartilages. The two inner angles of the arytenoid 

 cartilages are drawn together by the contraction of certain 

 muscles, while others contract to stretch the vocal cords. 

 The thyroid and cricoid cartilages move upon each other 

 to assist in the process. The muscles of the thorax and 

 the abdomen are also brought into special action, and the 

 column of air in the air chamber composed of the trachea 

 and the bronchial system is thrown into vibration. Sound 

 is a result of the whole process. 



188. The Resonating Cavities (Fig. 82). The pharynx, 

 the mouth, and the nasal chambers are resonating cavities, 

 which, by very slight changes in form and size, are able 

 to bring into special prominence different parts of the 

 general tone produced in the larynx, and so modify the 

 resulting sound. 



189. Speech is the enunciation of articulate sounds to 

 express thought, and is the result of the action of the vol- 

 untary muscles by which the vibrations produced in the 

 larynx are modified in the resonating cavities. The fac- 

 ulty of speech is a distinctive gift of man, and is possessed 

 by no other animal. It is a natural gift, but its use is the 



